Control system and control method for guiding a motor vehicle along a path and for avoiding a collision with another motor vehicle

ABSTRACT

A control system which for use in a host motor vehicle is configured and intended for recognizing motor vehicles traveling ahead, to the side, and/or behind and preferably stationary objects situated ahead, based on surroundings data obtained from at least one surroundings sensor associated with the host motor vehicle. The at least one surroundings sensor is configured for providing an electronic controller of the control system with surroundings data that represent an area in front of, next to, or behind the host motor vehicle. The control system is at least configured and intended for detecting another motor vehicle, using the road, relative to the host motor vehicle by means of the at least one surroundings sensor, and determining movements of the other motor vehicle relative to a lane in which the other motor vehicle or the host motor vehicle is present, or relative to the host motor vehicle, determining, starting from an instantaneous location of the host vehicle, a set having a predefined number of trajectories, differing with regard to their length and/or their course, for possible paths of the host motor vehicle, wherein the course of neighboring trajectories differs by a predefined difference between possible different steering angles of the host motor vehicle, correlating the course of the determined trajectories for possible paths of the host motor vehicle with the provided surroundings data, and classifying the determined trajectories as trajectories involving a collision, collision-free trajectories, and/or optimal trajectories, determining an instantaneously traveled trajectory of the host motor vehicle and comparing it to the classified trajectories, and based on this situation recognition for the host motor vehicle, making an intervention decision, and generating at least one signal that assists a driver of the host motor vehicle in controlling the host motor vehicle in order to guide the host motor vehicle at least along a collision-free trajectory, or generating at least one associated control command that causes the host motor vehicle to follow at least one of the collision-free trajectories.

RELATED APPLICATION

This application claims priority from German Application No. 10 2016 009764.7, filed Aug. 11, 2016. the subject matter of which is incorporatedherein by reference in its entirety

BACKGROUND OF THE INVENTION

A control system and a control method for avoiding a collision with apreceding motor vehicle during a lane change are disclosed herein. Thiscontrol system and control method are based in particular on asurroundings sensor system in the host motor vehicle, and assist adriver or an autonomously driving motor vehicle. The aim is to increasethe safety of the occupants of the motor vehicle for semiautonomousmotor vehicles and autonomously controlled motor vehicles.

Prior Art

Present driver assistance systems (advanced driver assistance systems(ADAS)) provide numerous monitoring and information functions in motorvehicles in order to make driving a motor vehicle safer. Thesurroundings of the motor vehicle are hereby monitored with regard tothe travel course of the host motor vehicle, based on surroundings dataobtained from one or more surroundings sensors situated on the motorvehicle.

Known driver assistance systems determine, for example, whether themotor vehicle is present within a lane, and whether the driver isunintentionally drifting to one side of the lane or is about to leavethe lane. These driver assistance systems generate from the obtainedsurroundings data a “map” of the roadway and in particular of the lane.In the process, objects such as curbs, lane boundary Hoes, directionalarrows, etc. are recognized and tracked during driving.

Present driver assistance systems also include so-called “blind spotmonitors.” These monitors determine, for example by means of radar,LIDAR, video, or the like, whether another motor vehicle, a road user,or an object is located to the side of and/or behind the motor vehicle,in which case a lane change or a turn by the host motor vehicle couldresult to a collision with same.

In addition, automatic speed control of the host motor vehicle isadapted to the speed of a preceding motor vehicle in so-called adaptivecruise control (ACC) systems. The intent is to always maintain a certaindistance from the preceding motor vehicle. For this purpose, these typesof systems determine a direction of movement and/or a speed of thepreceding motor vehicle m order to avoid the host motor vehicle crossingthe path of the preceding motor vehicle in such a way that a criticalsituation arises. This concerns lane change or turning operations on theone hand, and the avoidance of rear-end collisions on the other hand.

A speed controller in a motor vehicle which controls the distance from apreceding motor vehicle, and an emergency braking assistant in a motorvehicle, are driver assistance systems that react to other road users,for example other motor vehicles or pedestrians. For this purpose, themost relevant road user is selected in order to carry out an appropriateaction.

This so-called route selection or destination selection frequently takesplace by estimating the trajectory of the host motor vehicle andselecting the road user that is present on this trajectory. Estimatingthe trajectory is generally based on the knowledge of a speed and a yawrate of the host motor vehicle, as well as other available informationsuch as roadway markers.

One procedure in collision avoidance systems or automated drivingincludes computation of a path or trajectory for the host motor vehicleand subsequent attempts to guide the vehicle along the path/trajectoryvia a controller. However, during the planning, the dynamics of theclosed control loop are usually not correctly taken into account, anddesigning vehicle controllers is complicated. Alternatively, a modelpredictive method is occasionally used which addresses both aspects inone step and takes the control dynamics into account with sufficientaccuracy. However, this requires a very high level of computationaleffort, which in any case is not justifiable in series productionvehicles for the foreseeable future.

Another approach is a model predictive trajectory set method. However,this method provides only a suboptimal solution for the optimal controlproblem due to its relatively coarse discretization of the controlsequence. However, the planning and control are carried out in one step,and a dynamic, realistic model is explicitly taken into account.

In motor vehicles that are driven by persons, the driver assistancesystems usually provide an information function in order to warn thedriver of a critical situation or an appropriate maneuver, or to suggestto the driver a suitable maneuver for the host motor vehicle. Similarly,the driver assistance systems may also be used in autonomouslycontrolled motor vehicles in order to provide the autonomous controlsystem with the appropriate surroundings data.

The technological background in this regard is discussed in thepublications “Ein modellprädikitives Planungs- undFahrzeugquerregelungsverfahren zur Kolllsionsverrneidung durchNotausweichmanöver” [A model predictive planning and vehicle lateralcontrol method for avoiding collisions by emergency evasive maneuvers]byKeller, M, Haβ, C., Seewakt A., and Bertram, T. in Automotive meetsElectronics, Feb. 24-25, 2015, Dortmund, February 2015, and “A ModelPredictive Approach to Emergency Maneuvers in Critical TrafficSituations” by Keller, M., Haβ, C., Seewald, A.s and Bertram, T. in IEEEIntelligent Transportation System Conference, Las Palmas de Gran Canada,September 2015.

Underlying Problem

On roadways having multiple lanes in a travel direction, a lane changeby a motor vehicle can have fatal consequences if, during the lanechange by the host motor vehicle, the behavior of a preceding motorvehicle is incorrectly evaluated, incorrectly recognized, or recognizedtoo late by a driver or a driver assistance system of the host motorvehicle. This applies, for example, for a slowing down of the precedingmotor vehicle, on which the host motor vehicle, which is changing to theadjacent lane, could “get caught.” This plays a role, for example, whenthe host motor vehicle changing to the adjacent lane is usually movingfrom a “slower” lane into a “faster” lane (i.e., in continental Europeor the United States, for example, from the right lane into the leftlane). In Germany, for example, great differences in speed may existbetween a preceding motor vehicle on the “slower” lane and a followingmotor vehicle on the “faster” lane, which the host motor vehiclechanging to the adjacent lane most overcome so that, for example,following vehicles in the faster lane are not held up.

On account of such a speed difference to be achieved, for example amisjudgment or an initiation of the lane change of the host motorvehicle that is incorrect or too late may result in a collision with thepreceding motor vehicle. Only strong braking or avoidance maneuvers canpossibly prevent a rear-end collision. For motor vehicles that arefollowing the host motor vehicle, this may result in braking operationsand/or driving maneuvers by the following motor vehicle which areotherwise unnecessary. Such unnecessary braking operations and/ordriving maneuvers may also endanger other road users and/or adverselyaffect driving comfort.

The object, therefore, is to provide a control system and a controlmethod for a motor vehicle for guiding the motor vehicle along a pathand for avoiding a collision with a preceding motor vehicle during alane change.

Proposed Solution

This object is achieved by a control system and a control method havingthe features of the respective independent claims.

A control system that is configured and intended for use in a host motorvehicle recognizes preceding motor vehicles and preferably stationaryobjects situated ahead, based on surroundings data obtained from atleast one surroundings sensor associated with the host motor vehicle.The at least one surroundings sensor is configured for providing anelectronic controller of the control system with surroundings data thatrepresent an area in front of the host motor vehicle. The control systemis at least configured and intended for determining, starting from aninstantaneous location, a set having a predefined number oftrajectories, differing with regard to their length and/or their course,for possible paths of the host motor vehicle, wherein the course ofneighboring trajectories differs by a predefined difference betweenpossible different steering angles of the host motor vehicle, and forvarying the predefined number of trajectories, the length, and/or thecourse of the trajectories as a function of a driving situation of thehost motor vehicle. The control system is at least configured andintended for generating at least one signal that assists a driver of thehost motor vehicle in controlling the host motor vehicle in order toguide the host motor vehicle along a selected one of these trajectories,or for generating at least one associated control command that causesthe host motor vehicle to follow a selected one of these trajectories.

One aspect relates to the control system that is configured and intendedfor use in a host motor vehicle. The control system that is configuredand intended for this purpose may vary the predefined number oftrajectories, the length, and/or the course of the trajectories as afunction of the following aspects of the driving situation of the hostmotor vehicle: (i) the speed of the host motor vehicle, (ii) a lateral,rear, and/or frontal distance from another motor vehicle using the road,relative to the host motor vehicle, (iii) a relative speed betweenanother motor vehicle using the road and the host motor vehicle, and/or(iv) a roadway course in front of the host motor vehicle.

In determining the trajectories for possible paths of the host motorvehicle, in a first discretization step (i) the number of trajectoriesmay be specified to be a first number of approximately 3 to 15, and/or(ii) the difference between possible different steering angles of thehost motor vehicle may be specified to remain the same or to increasewith an increasing different steering angle, by the control system thatis configured and intended for this purpose.

In determining the trajectories for possible paths of the host motorvehicle, in a following discretization step the control system may alsobe configured and intended for (i) specifying the number of trajectoriesto be a second, lower number of approximately 3 to 5, and/or (ii)reducing the difference between possible different steering angles ofthe host motor vehicle.

Compared to conventional driver assistance systems, the approachpresented here improves a low-risk execution of a lane change of thehost motor vehicle relative to a preceding motor vehicle. The host motorvehicle hereby preferably changes from a “slower” lane to a “faster”lane. This low-risk execution of a lane change is achieved in particularin that the control system is able to determine “incorrect” or“unfavorable” trajectories, and is configured for keeping the driverfrom using these “incorrect” or “unfavorable” trajectories.

In addition, the system may merely suggest that the driver change fromtrajectories that are instantaneously evaluated as critical to a lesscritical, or even favorable, or even an instantaneously optimaltrajectory. Thus, use of the system is not limited to “emergencysituations,” and instead may be used in many situations. One(semi)autonomous intervention option by the system is a steering torqueoverlay.

Alternatively or additionally, the driver may be optically, haptically,or acoustically advised by the system to leave such a criticaltrajectory.

A system that is able to determine the “best” trajectory in allconceivable situations, in particular emergency situations, for example,requires a significant outlay of sensor and computing resources. Forexample, extremely complex situations must be processed on multilanefreeways. In a considerable number of scenarios, determining the “best”trajectory for the host motor vehicle is not possible at all due to thelack of information concerning all possible obstruction trajectories.

Therefore, the system presented here takes a different approach. Thisdoes not involve bringing the host motor vehicle to the trajectory thatis instantaneously evaluated as the “correct” one. Instead, the hostmotor vehicle is diverted from trajectories that are instantaneouslyevaluated as “incorrect.”

The system presented here identifies “incorrect” or “unfavorable”trajectories and (i) signals this to the driver or (ii)(semi)autonomously intervenes in the driving behavior, for example by abraking or steering torque overlay in the host motor vehicle.

Thus, use of the system is not limited to emergency situations, andinstead may be used in many situations. It is also conceivable to usemanipulated variables other than the steering torque overlay.

For this purpose, a control system that is configured and intended foruse in a host motor vehicle is used to recognize, based on surroundingsdata obtained from at least one surroundings sensor associated with thehost motor vehicle, preceding motor vehicles and preferably stationaryobjects situated ahead, wherein the at least one surroundings sensor isconfigured for providing an electronic controller of the control systemwith surroundings data that represent an area in front of, next to,and/or behind the host motor vehicle, and wherein the control system isat least configured and intended for detecting another motor vehicle,using the road, in front of the host motor vehicle by means of the atleast one surroundings sensor, and determining movements of the othermotor vehicle relative to (i) a lane in which the other motor vehicle orthe host motor vehicle is present, or (ii) the host motor vehicle.Starting from an instantaneous location, the control system determines aset having a predefined number of trajectories, differing with regard totheir length and/or their course, for possible paths of the host motorvehicle, wherein the course of neighboring trajectories differs by apredefined difference between possible different steering angles of thehost motor vehicle.

The control system is configured and intended for correlating the courseof the determined trajectories for possible paths of the host motorvehicle with the provided surroundings data, classifying the determinedtrajectories as (i) trajectories involving a collision, (ii)collision-free trajectories, and/or (iii) optimal trajectories,determining an instantaneously traveled trajectory of the host motorvehicle and comparing it to the classified trajectories, and based onthis situation recognition for the host motor vehicle, making anintervention decision, and generating at least one signal that assists adriver of the host motor vehicle in controlling the host motor vehiclein order to guide the host motor vehicle at least along a collision-freetrajectory, or generating at least one associated control command thatcauses the host motor vehicle to follow at least one of thecollision-free trajectories.

The control system is configured and intended for the signal to initiatean intermittent braking or steering torque overlay in the host motorvehicle, wherein successive individual overlays are spaced at timeintervals such that the driver perceives them as a separate interventionin terms of a steering suggestion or directional information.

In one variant, the signal is designed as a pulse that rises morequickly than it falls. A sawtooth pulse is one possible signal form bymeans of which the driver clearly perceives the pulse as a braking orsteering torque overlay in the host motor vehicle. However, other pulseforms are also possible.

These system variants allow collision avoidance in emergency situationsand recognize unequivocal driver errors; for example, if the driversteers the host motor vehicle into an obstacle or destabilizes the hostmotor vehicle, a signal is emitted to warn the driver, or a braking orsteering torque overlay in the host motor vehicle immediately takesplace. For example, in right-hand traffic on a curved highway, if thedriver cuts a corner on a tight curve to the left and is at risk ofcolliding with an oncoming vehicle, a signal is emitted to warn thedriver, or a braking or steering torque overlay in the host motorvehicle immediately takes place. For example, if the driver cuts a curveand is at risk of contacting the curb, a signal is emitted to warn thedriver, or a braking or steering torque overlay in the host motorvehicle immediately takes place. For example, if the driver starts topass on a freeway and falls to observe traffic in the adjacent lane, asignal is emitted to warn the driver, or a braking or steering torqueoverlay in the host motor vehicle immediately takes place.

This allows an increase in driving safety and driving comfort, in thatduring a lane change by the host motor vehicle, possible problems due toa preceding other motor vehicle are recognized correctly and in a timelymanner, and a speed adaptation and/or a driving maneuver of the hostmotor vehicle may thus be carried out either by the driver or by adriver assistance system in order to avoid an accident.

A discretization of adaptive manipulated variables may be carried out bythe system in determining the trajectories, which represents animportant aspect for implementation in the motor vehicle. For a fixeddiscretization, the trajectories can have only fixed, discrete radii ofcurvature or trajectory lengths along which the host motor vehicle isdriven. If, for example, the host motor vehicle is traveling on afreeway exit having a radius of curvature of the roadway that happens tonot be a part of the discrete quantity of possible radii of curvature ofthe trajectories, a switch must continuously be made back and forthbetween two (unsuitable) radii of curvature of the trajectories in orderto at least approximate the radius of curvature of the roadway. Thisresults in oscillations in the host motor vehicle, and thus, unsuitabledriving behavior.

In the adaptive discretization presented here, the instantaneouslypossible or employed control range of the trajectory of the host motorvehicle is specified in a first discretization step. More fine-tuneddiscretization is then carried out in a second discretization step. Thistwo-step concept allows virtually quasi-continuous readjustment. Thus,practically any given radius of curvature of the trajectory to betraveled may be achieved with comparatively little computational effort,and thus, very quickly.

By means of the control system, in contrast to conventional driverassistance systems, a misjudgment of an unsteady driving behavior of theother motor vehicle during the lane change of the host motor vehicle maybe avoided or at least reduced. If the control system determines, forexample, a lateral movement of the other motor vehicle relative to theassociated lane in which the other motor vehicle is present, this may beregarded as “critical” in the determination of possible trajectories. Ifthe driver of the host motor vehicle should pursue one of thesetrajectories, this is signaled as unfavorable; in a further scenario thecontroller intervenes m the steering/driving process.

In one variant, the control system is also configured and intended foremitting a signal that is suitable for warning a driver of the hostmotor vehicle of critical trajectories. The control system may thusassist the driver of the host motor vehicle in taking suitable measures.Additionally or alternatively, the signal may be suitable for carryingout an autonomous trajectory adaptation and/or speed adaptation of thehost motor vehicle, and/or for taking this into account for anautonomous lane change or autonomous driving maneuver by the host motorvehicle.

The control system may ascertain the host lane and the other lane, forexample based on surrounding features such as lane boundaries and/orlane markers. The control system may likewise ascertain thesesurrounding features based on surroundings data obtained by means of theat least one surroundings sensor. In addition, the control system mayalso be provided with the surrounding features by an external system,for example a GPS system.

Furthermore, the control system may be configured and intended fordetecting, over a predetermined time period or continuously, the othermotor vehicle using the road, by means of the at least one surroundingssensor in order to determine the lateral movement of the other motorvehicle, it is thus possible for the control system to more reliablydetermine whether an instantaneous lateral movement of the other motorvehicle signifies a lane change, or whether this instantaneous lateralmovement of the other motor vehicle is due to the individual drivingbehavior of the driver of the other motor vehicle.

The lateral movement of the other motor vehicle may be determined basedon position values and/or lateral speed values.

The control system may also be configured and intended for determiningthe lateral movement of the other motor vehicle, and determining, duringthe predetermined time period or continuously, a change in a distancebetween a longitudinal axis of the other motor vehicle and a centerline,at least one lane boundary, or at least one lane marker of theassociated lane in which the other motor vehicle is present. Thecenterline and the lane boundary of the associated lane may be avirtual, instantaneous centerline or instantaneous lane boundary of theassociated lane that is determined by the control system. Similarly, thecontrol system may determine, during the predetermined time period orcontinuously, a change in the distance between a longitudinal axis ofthe other motor vehicle and a virtual or real lane marker or laneboundary on which the host motor vehicle is present.

In one refinement, the control system may be configured and intended fordetermining the instantaneous traffic situation of other motor vehiclesusing the road, and/or detecting objects in front of the host motorvehicle, by means of the at least one surroundings sensor. These othermotor vehicles and/or objects may be present in an area directly infront of the host motor vehicle as well as in an area at a fartherdistance away, depending on the surroundings sensor used. It isunderstood that multiple surroundings sensors may also be used in thecontrol system in order to detect the other motor vehicle, additionalmotor vehicles, objects, and/or other surrounding features on which thesurroundings data are based.

The control system may also establish that no additional motor vehiclesand/or objects are present in front of, next to, and/or behind the hostmotor vehicle.

The control system may be configured and intended for determining theinstantaneous traffic situation at a distance between the other motorvehicle and an additional motor vehicle or object located in front ofthe other motor vehicle, as well as a speed difference between the othermotor vehicle and the additional motor vehicle or object located infront of the other motor vehicle, wherein the other motor vehicle andthe additional motor vehicle or object located in front of the othermotor vehicle are present in the same lane or an adjacent lane.

For example, if the determined distance is small, while the determinedspeed difference is large, in the adaptive discretization presented herethe instantaneously possible or employed control range of the trajectoryof the host motor vehicle is specified in a first discretization step.More fine-tuned discretization is then carried out in a seconddiscretization step. This allows virtually quasi-continuousreadjustment. Thus, a sufficient selection of low-risk trajectories forthe instantaneous driving situation of the host motor vehicle may bedetermined in a practical manner with comparatively little computationaleffort, and thus, very quickly.

The control system may be configured and intended for determining theinstantaneous traffic situation at a distance between the other motorvehicle and a motor vehicle or object that is offset in front of theother motor vehicle, and for determining a speed difference between theother motor vehicle and the motor vehicle or object that is offset infront of the other motor vehicle, wherein the other motor vehicle andthe motor vehicle or object that is offset in front of the other motorvehicle are present in different lanes. For example, the offset motorvehicle or object may be present in the same lane as the host motorvehicle.

It is apparent to those skilled in the art that the aspects and featuresdescribed above may be arbitrarily combined in a control system and/or acontrol method. Although some of the above-described features have beenexplained with reference to a control system, it is understood thatthese features may also apply to a control method. Likewise, thefeatures described above with reference to a control method maycorrespondingly apply to a control system.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aims, features, advantages, and possible applications resultfrom the following description of exemplary embodiments, which are notto be construed as limiting, with reference to the associated drawings.All features described and/or graphically illustrated, alone or in anycombination, constitute the subject matter disclosed herein. Thedimensions and proportions of the components shown in the figures arenot to scale.

FIG. 1 schematically shows a host motor vehicle, in which a sequence oftrajectory sets, detected by means of a first control system in an areain front of the host motor vehicle, is computed, on the basis of which atrajectory for a segment in each case establishes the travel path of thehost motor vehicle.

FIG. 2 schematically shows the host motor vehicle, in which a secondcontrol system generates a sequence of trajectories and associatedsignals or control commands for passing a preceding motor vehicle, andwhen the trajectories for possible travel paths of the host motorvehicle are determined, a two-step adaptive discretization takes place.

FIG. 3 schematically shows the host motor vehicle, in which the controlsystem determines only a few different linear different trajectories.

FIG. 4 schematically shows the host motor vehicle, in which the controlsystem, starting from an instantaneous location of the host motorvehicle, determines a set having a predefined number of differenttrajectories, with regard to their length and/or their course, forpossible paths of the host motor vehicle.

FIG. 5 shows a diagram of the different effect of a linear, equidistantdiscretization and the two-step or multi-step adaptive discretizationfor computing the trajectory set for possible travel paths of the hostmotor vehicle.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a host motor vehicle 10 that is present inthe right lane 12 of a roadway 14. An additional, left lane 16 of theroadway 14 is situated next to the right lane 12. The right lane 12 andthe left lane 16 of the roadway 14 are separated from one another by adashed-line roadway marker 18.

The host motor vehicle 10 has at least one surroundings sensor (notshown) that is associated with the host motor vehicle 10 and mountedthereon. The surroundings sensor may be designed, for example, in theform of a camera, although use of other known surroundings sensors(radar, LIDAR, ultrasound, etc.) is also possible. The at least onesurroundings sensor is configured for detecting an area in front of thehost motor vehicle 10, and providing the surroundings data thatrepresent this area to an electronic controller (not shown) of a controlsystem (not shown) installed in the host motor vehicle 10. In theexample shown in FIG. 1, a first control system detects the other motorvehicle 20 by means of the at least one surroundings sensor. The hostmotor vehicle 10 is traveling toward the other motor vehicle 20 at aspeed that is greater than the speed of the other motor vehicle 20. Forthis reason, the host motor vehicle 10 in the situation shown in FIG. 1makes a lane change from the right lane, along a sequence oftrajectories 30, to the left lane.

It is explained below how the traveled sequence of trajectories 30 comesabout due to the control system.

The control system detects one or more other motor vehicles 20, usingthe road, in front of the host motor vehicle 10 by means of the at leastone surroundings sensor, and determines movements of the other motorvehicle 20 relative to a lane 12, 16 in which the other motor vehicle 20or the host motor vehicle 10 is present, or (ii) relative to the hostmotor vehicle 10. Starting from an instantaneous location of the hostmotor vehicle 10, the control system determines a set having apredefined number of trajectories, differing with regard to their lengthand/or their course, for possible paths of the host motor vehicle 10.The course of neighboring trajectories differs by a predefineddifference between possible different steering angles of the host motorvehicle 10. In one variant of the control system, this procedure iscarried out approximately every 20 ms; during this time periodapproximately 15 possible trajectories are computed.

Starting from the set of trajectories determined in each case in thismanner, their predefined number, their length, and/or their courseare/is varied as a function of a driving situation of the host motorvehicle 10.

This variation takes place in the control system as a function of thefollowing aspects of the driving situation of the host motor vehicle 10:(i) the speed of the host motor vehicle (10)—the higher the speed of thehost motor vehicle, the longer the individual computed trajectory of theset; (ii) a lateral, rear, and/or frontal distance from another motorvehicle 20 using the road, relative to the host motor vehicle 10—thesmaller the distance, the smaller the angular distance betweenneighboring trajectories of the set; (iii) a relative speed between theother motor vehicle 20 and the host motor vehicle 10—the higher therelative speed, the longer the individual computed trajectory of the setand the smaller the angular distance between neighboring trajectories ofthe set; and/or (iv) a roadway course in front of the host motor vehicle10—the smaller the radius of curvature, the shorter the individualcomputed trajectory of the set, and the smaller the angular distancebetween neighboring trajectories of the set.

In one variant the control system carries out a two-step procedure indetermining the trajectories for possible paths of the host motorvehicle 10 (see FIG. 2). In a first discretization step,

(i) the number of trajectories is specified to be approximately 3 to 15and (ii) the difference between possible different steering angles ofthe host motor vehicle 10 is specified to remain the same or to increasewith an increasing different steering angle. It is assumed that it ismore unlikely that larger steering angles (>+/−20°, for example) areadopted than smaller steering angles (<+/−20, for example).

In a subsequent discretization step, for determining the trajectoriesfor possible paths of the host motor vehicle 10, the control system (i)reduces the number of trajectories to approximately 3 to 5, and (ii)reduces the difference between possible different steering angles of thehost motor vehicle 10 to approximately 2°.

Based on these trajectory data, the control system generates at leastone signal that assists a driver of the host motor vehicle incontrolling the host motor vehicle in order to guide the host motorvehicle 10 along a selected one of these trajectories, or generates atleast one associated control command that causes the host motor vehicle10 to follow a selected one of these trajectories. In other words: Thecurve is approximately implemented in the first step (A in FIG. 2).Discretization in small increments is then performed around thisapproximate solution in the next step. The discretization “converges” atthe required steering angle. It is thus possible to achieve any drivablecurvature in a steady-state manner without switching back and forthbetween only approximately matching radii of curvature (B in FIG. 2).

The advantageous effect of this procedure is clear with respect to thesituation in FIG. 2 compared to FIG. 3, if the control system of thehost motor vehicle 10 determines only a few different trajectories, asshown in FIG. 3, in order to be prepared for all contingencies thesetrajectories must provide a relatively large difference (in the presentcase, approximately 35°) between adjacent possible steering angles ofthe host motor vehicle 10. When negotiating a curve, it is highlyunlikely that one of the predefined steering angles exactly matches thecurvature of the curve. Therefore, the control system of the host motorvehicle 10 must make readjustments in increments, using another of thepredefined steering angles. As a result, the host motor vehicle 10 wouldnegotiate the curve in a lurching manner (see FIG. 3).

In other words: Of the three possible trajectories, none exactlyimplements the roadway course. A switch must always be made back andforth between two solutions.

As illustrated in FIG. 4, the control system of the host motor vehicle10, starting from an instantaneous location of the host motor vehicle10, determines a set having a predefined number of trajectories,differing with regard to their length and/or their course, for possiblepaths of the host motor vehicle 10. The course of neighboringtrajectories differs by a predefined difference between possibledifferent steering angles of the host motor vehicle. In the example inFIG. 4, this is approximately 4° in each case. In addition, the controlsystem of the host motor vehicle 10 correlates the course of thedetermined trajectories for possible paths of the host motor vehicle 10with the provided surroundings data. If one of the trajectories collideswith objects (other vehicles, roadway boundaries, or the like), it isclassified as a trajectory involving a collision. If a trajectory doesnot encounter an object over its length, it is classified as acollision-free trajectory. As a result of this procedure, all determinedtrajectories are classified as (i) trajectories involving a collision,(ii) collision-free trajectories, and/or (iii) optimal trajectories, asillustrated in FIG. 4.

In this regard, the indicated reference characters denote the following:a: if the host motor vehicle is guided on one of these trajectories, itwill collide; b: Optimal trajectory; c: Collision-free trajectories.

It is not mandatory for a trajectory to also be classified as an optimaltrajectory. Rather, it is sufficient to make a distinction betweentrajectories involving a collision and collision-free trajectories.

The control system of the host motor vehicle 10 subsequently determinesa/the instantaneously traveled trajectory of the host motor vehicle 10and compares it to the classified trajectories. Starting from thissituation recognition for the host motor vehicle 10, the control systemof the host motor vehicle 10 makes an intervention decision to generateat least one signal that assists a driver of the host motor vehicle 10in controlling the host motor vehicle 10 in order to guide it at leastalong one of the collision-free trajectories. In a (semi)autonomousdriving mode, at least one associated control command is generated thatcauses the host motor vehicle 10 to follow at least one of thecollision-free trajectories.

In one variant of the control system, the signal is designed as anintermittent braking or steering torque overlay in the host motorvehicle, which is set by suitable actuators (not illustrated) for asteering gear or a vehicle braking system. In one embodiment of thecontrol system, successive individual overlays are spaced at timeintervals such that the driver perceives them at the steering wheel as aseparate intervention in terms of a steering suggestion or directionalinformation.

FIG. 5 illustrates the difference between a linear, equidistantdiscretization of the steering wheel angle and an adaptivediscretization of the steering wheel angle. In this example, tendiscrete steering angles are illustrated from −200° to +200° atintervals of 50°. If a steering angle of 90° were required in a steeringsituation, for a linear, equidistant discretization of the steeringwheel angle the closest steering wheel angle of 100° would be set, butthe trajectories of the other ten discrete steering wheel angles between−200° and +200° would also be computed. In the adaptive discretizationof the steering wheel angle presented here, the ten discrete steeringwheel angles between −100° to +100° are computed in the next step,whereby more trajectories are computed in the vicinity of theinstantaneous steering wheel angle of 90° than farther away from thisangle. One trajectory is computed at −100°, one is computed near 0°, andone is computed near 200°; six different trajectories situated veryclose to one another are computed near the instantaneous steering wheelangle of 90°. This procedure allows a very efficient determination ofcollision-free trajectories, which the control system can facilitate byemitting appropriate signals for the steering torque overlay, forexample.

It is understood that the exemplary embodiments explained above are notexhaustive, and do not limit the subject matter disclosed herein. Inparticular, it is apparent to those skilled in the art that they maycombine the features of the various embodiments with one another and/oromit various features of the embodiments without thereby departing fromthe subject matter disclosed herein.

The invention claimed is:
 1. A control system which for use in a hostmotor vehicle (10) is configured and intended for recognizing motorvehicles traveling ahead, to the side, and/or behind and preferablystationary objects situated ahead, based on surroundings data obtainedfrom at least one surroundings sensor associated with the host motorvehicle (10), wherein the at least one surroundings sensor is configuredfor providing an electronic controller of the control system withsurroundings data that represent an area in front of, next to, or behindthe host motor vehicle, the control system comprising: detecting anothermotor vehicle (20) using the road, relative to the host motor vehicle(10), by means of the at least one surroundings sensor, determiningmovements of the other motor vehicle (20) relative to (i) a lane inwhich the other motor vehicle (20) or the host motor vehicle (10) ispresent, or (ii) the host motor vehicle, determining, starting from aninstantaneous location of the host motor vehicle (10), a set having apredefined number of trajectories, differing with regard to their lengthand/or their course, for possible paths of the host motor vehicle (10),wherein the course of neighboring trajectories differs by a predefineddifference between possible different steering angles of the host motorvehicle (10), correlating the course of the determined trajectories forpossible paths of the host motor vehicle (10) with the providedsurroundings data, and classifying the determined trajectories as (i)trajectories involving a collision, (ii) collision-free trajectories,and/or (iii) optimal trajectories, determining an instantaneouslytraveled trajectory of the host motor vehicle (10) and comparing it tothe classified trajectories, and based on this situation recognition forthe host motor vehicle (10), making an intervention decision, andgenerating at least one signal that assists a driver of the host motorvehicle (10) in controlling the host motor vehicle (10) in order toguide the host motor vehicle (10) at least along a collision-freetrajectory, or generating at least one associated control command thatcauses the host motor vehicle (10) to follow at least one of thecollision-free trajectories.
 2. The control system according to claim 1,which is configured and intended for initiating the signal as anintermittent braking or steering torque overlay in the host motorvehicle, wherein successive individual overlays are preferably spaced attime intervals such that the driver perceives them as a separateintervention in terms of a steering suggestion or directionalinformation.
 3. The control system according to claim 1, wherein thesignal is designed as a pulse that rises more quickly than it falls. 4.A control method which for use in a host motor vehicle (10) isconfigured and intended for recognizing motor vehicles traveling ahead,to the side, and/or behind and preferably stationary objects situatedahead, based on surroundings data obtained from at least onesurroundings sensor associated with the host motor vehicle (10), whereinthe at least one surroundings sensor is configured for providing anelectronic controller with surroundings data that represent an area infront of, next to, or behind the host motor vehicle, and the controlmethod comprising: detecting another motor vehicle (20) using the road,relative to the host motor vehicle (10), by means of the at least onesurroundings sensor, determining movements of the other motor vehicle(20) relative to (i) a lane in which the other motor vehicle (20) or thehost motor vehicle (10) is present, or (ii) the host motor vehicle,determining, starting from an instantaneous location of the host motorvehicle (10), a set having a predefined number of trajectories,differing with regard to their length and/or their course, for possiblepaths of the host motor vehicle (10), wherein the course of neighboringtrajectories differs by a predefined difference between possibledifferent steering angles of the host motor vehicle, correlating thecourse of the determined trajectories for possible paths of the hostmotor vehicle (10) with the provided surroundings data, and classifyingthe determined trajectories as (i) trajectories involving a collision,(ii) collision-free trajectories, and/or (iii) optimal trajectories,determining an instantaneously traveled trajectory of the host motorvehicle (10) and comparing it to the classified trajectories, and basedon this situation recognition for the host motor vehicle (10), making anintervention decision, and generating at least one signal that assists adriver of the host motor vehicle (10) in controlling the host motorvehicle (10) in order to guide the host motor vehicle (10) at leastalong a collision-free trajectory, or generating at least one associatedcontrol command that causes the host motor vehicle (10) to follow atleast one of the collision-free trajectories.
 5. The control methodaccording to claim 4, which is configured and intended for initiatingthe signal as an intermittent braking or steering torque overlay in thehost motor vehicle, wherein successive individual overlays arepreferably spaced at time intervals such that the driver perceives themas a separate intervention in terms of a steering suggestion ordirectional information.
 6. The control method according to claim 4,wherein the signal is designed as a pulse that rises more quickly thanit falls.
 7. A method of controlling a host motor vehicle having atleast one surroundings sensor for obtaining surroundings data around thehost motor vehicle, comprising: detecting another vehicle on the roadwith the at least one surroundings sensor; determining movements of theanother vehicle; determining a series of possible trajectories for thehost motor vehicle which differ from one another by a predefinedsteering angle; correlating the possible trajectories with thesurroundings data such that each determined possible trajectory can beclassified as (i) a trajectory involving a collision, (ii) acollision-free trajectory or (iii) an optimal trajectory; comparing theclassified trajectories to an instantaneous trajectory of the host motorvehicle; and generating at least one signal to assist moving the hostmotor vehicle from the instantaneous trajectory to one of thecollision-free trajectories or optimal trajectories.
 8. The controlmethod of claim 7, wherein generating at least one signal comprisesgenerating a signal that assists a driver of the host motor vehicle inmoving the host motor vehicle from the instantaneous trajectory to oneof the collision-free trajectories or optimal trajectories.
 9. Thecontrol method of claim 7, wherein generating at least one signalcomprises generating a command signal that causes the host motor vehicleto autonomously move from the instantaneous trajectory to one of thecollision-free trajectories or optimal trajectories.